What is Nipah Virus?
Nipah virus (NiV) belongs to the family Paramyxoviridae, genus Henipavirus. Initially, the Nipah Virus was isolated and identified when encephalitis and respiratory illness was spread amongst the people that were in close contact with pigs including the pig farmers of Malaysia and Singapore. The name Nipah come from a village in the Malaysian Peninsula where the pig farmers were attacked by the encephalitis illness named Sungai Nipah. The NiV was found to be related with Hendra virus, so all the species of bats were singled out real quick to be investigated and the flying foxes belonging to the genus Pteropus were later identified to be the reservoir for NiV.
The first outbreak took place in 1999, a relatively mild disease was caused by the Virus in the pigs, but in humans, about 300 cases were found and over 100 of them died. More than a million pigs were euthanized in order to stop the outbreak, which caused a very huge loss to Malaysia. After that, no similar outbreak has been reported in neither any human or pigs in both Malaysia or Singapore.
NiV caused another disease outbreak in 2001, occurring in Bangladesh. The Virus was confirmed to be Nipah Virus by the genetic sequencing but it was found to be different by a strand from the one identified before in 1999. Another outbreak was reported in Siliguri in the same year, reports of person to person transmission (nosocomial transmission) in a hospital were found in India. The outbreaks take place almost annually in Bangladesh and have been found many times in India since then, unlike the outbreak in Malaysia.
How does it spread?
Nipah Virus spreads when the person comes into direct contact with an infected bat or an infected pig or by getting in contact with a person infected with the same virus. The Humans were mainly infected by Nipah Virus Because of being in close contact with infected pigs. The Nipah Virus was initially transmitted from bats to pigs in the strain seen in the first outbreak, the pig population spread subsequently and so did the virus. The humans were infected by being in contact with the infected pigs. The person to person transmission of this virus was not reported in this outbreak. But in India and Bangladesh, the person to person outbreak is reported on a regular basis. In the family and caregivers of Nipah virus-infected patients, this is most commonly seen. From direct exposure to infected bats transmission also takes place. Raw date palm sap contaminated with infectious bat excretions cause the infection on consuming them.
Signs and Symptoms
The infection of Nipah Virus is linked with encephalitis (inflammation of the brain). After being exposed to the virus and the period of incubation of about 5 to 14 days, illness shows up with a fever and headache of about 3 to 14 days which is followed by drowsiness, disorientation and mental confusion. The person can get into a coma after these symptoms within 24 to 48 hours. Some patients feel worse in respiration in the early days of their infection, half of the patients showed severe neurological signs showed also pulmonary signs.
265 patients were infected with Nipah Virus during the Nipah Virus disease outbreak in 1998-99. 40% of the patients died from the illness who entered the hospital with a serious nervous disease. Following Nipah Virus infection Long-term sequelae have been noted which includes persistent convulsions and personality changes. After months and years of exposure, Latent infections with subsequent reactivation of Nipah virus and death have also been reported. In Malaysia and Singapore, the infection spread through the pig it was only related to the close contact with pigs that were infected with the virus. Consumption of raw date palm sap and contact with bats is the main cause of Nipah virus infection in India and Bangladesh. Human to human transmission of this virus is also a main cause of the Nipah Virus infection.
Laboratory diagnosis of a patient having a clinical history of NiV can be made during the acute and convalescent phases of the disease by using a combination of tests. Virus isolation attempts and real-time polymerase chain reaction (RT-PCR) from the throat and nasal swabs, cerebrospinal fluid, urine, and blood should be performed in the early stages of a disease. Antibody detection by ELISA (IgG and IgM) can be used later on. In fatal cases, immunohistochemistry on tissues collected during autopsy may be the only way to confirm a diagnosis.
The person infected with this virus must be taken to the hospital immediately. The treatment of Nipah Virus is limited to supportive care. Nipah Virus can spread from person to person therefore standard infection control practices and proper barrier nursing techniques are mandatory in order to prevent hospital-acquired infections (nosocomial transmission). The drug ribavirin has been proven to be effective against Nipah Virus in vitro, but human investigations that have been made to date had no conclusion and the clinical usefulness of ribavirin is still not certain.
Using a human monoclonal antibodies passive immunization in targeting the Nipah G glycoprotein has been evaluated in the post-exposure therapy in the ferret model and found to be of benefit.
By avoiding contact with sick pigs and bats in the area where the infection has been found and by not drinking the raw date palm sap Nipah Virus infection can be prevented. Future outbreaks will be prevented by taking the help of Additional efforts focused on surveillance and awareness. There is a need of research in order to understand the ecology of bats and the ecology of Nipah Virus, questions like the season in which the disease occurs and the reproductive cycle of bats need to be investigated. For early detection of the disease in people and the animal’s Surveillance tools should include reliable laboratory assays. The awareness shall be raised regarding the prevention and treatment of the Nipah Virus is very important in a reinforcement of standard infection control practices in order to avoid human to human transmission in the hospital (nosocomial infection).
In Australia, to protect horses against Hendra Virus A subunit vaccine, using the Hendra G protein is used. This protein produces cross-protective antibodies that protect us against HENV and NIPV. There is a great potential in this vaccine for protecting humans against henipavirus protection.